<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8" />
  <meta http-equiv="X-UA-Compatible" content="IE=edge" />
  <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  <link rel="stylesheet" href="./css/index.css" />
  <title>记事本</title>
</head>

<body>

  <!-- 主体区域 -->
  <section id="app">
    <!-- 输入框 -->
    <header class="header">
      <h1>小黑记事本</h1>
      <input v-model="taName" placeholder="请输入任务" class="new-todo" />
      <button @click="add" class="add">添加任务</button>
    </header>
    <!-- 列表区域 -->
    <section class="main">
      <ul class="todo-list">
        <li class="todo" v-for="(item, index) in todoList" key = "item.id">
          <div class="view">
            <span class="index">{{index + 1}}.</span> <label>{{item.name}}</label>
            <button class="destroy" @click="del(item.id)"></button>
          </div>
        </li>
      </ul>
    </section>
    <!-- 统计和清空 -->
     <!-- 没有任务时，底部隐藏 -->
    <footer class="footer" v-show="todoList.length > 0">
      <!-- 统计 -->
      <span class="todo-count">合 计:<strong> {{todoList.length}} </strong></span>
      <!-- 清空 -->
      <button @click="clear" class="clear-completed">
        清空任务
      </button>
    </footer>
  </section>

  <!-- 底部 -->
  <script src="./../vue.js"></script>
  <script>

    const app = new Vue({
      el: '#app',
      data: {
        taName: '',
        todoList: [
          { id: 1, name: '吃火锅'},
          { id: 2, name: '敲代码'},
          { id: 3, name: '学vue'},
        ]
      },
      methods: {
        del(id){
          this.todoList =this.todoList.filter(item => item.id !== id)
        },
        add(){
          if(this.taName.trim() === ''){
            alert('请输入任务')
            return
          }
          this.todoList.unshift({id : +Date.now(), name: this.taName})
          this.taName = ''
        },
        clear(){
          this.todoList = []
        }
      }
    })
// 添加功能：1，动态获取表单式的值（v-model），2，添加到数组中，3，清空输入框
// 删除功能：1，删除数组中的对应项，2，删除对应的li
// 统计功能：1，统计数组的长度，2，显示在页面上
  </script>
</body>

</html>